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<pre><span class="sourceLineNo">001</span>package com.github.sarxos.webcam;<a name="line.1"></a>
<span class="sourceLineNo">002</span><a name="line.2"></a>
<span class="sourceLineNo">003</span>import java.io.DataInputStream;<a name="line.3"></a>
<span class="sourceLineNo">004</span>import java.io.DataOutputStream;<a name="line.4"></a>
<span class="sourceLineNo">005</span>import java.io.EOFException;<a name="line.5"></a>
<span class="sourceLineNo">006</span>import java.io.File;<a name="line.6"></a>
<span class="sourceLineNo">007</span>import java.io.FileInputStream;<a name="line.7"></a>
<span class="sourceLineNo">008</span>import java.io.FileOutputStream;<a name="line.8"></a>
<span class="sourceLineNo">009</span>import java.io.IOException;<a name="line.9"></a>
<span class="sourceLineNo">010</span>import java.util.concurrent.atomic.AtomicBoolean;<a name="line.10"></a>
<span class="sourceLineNo">011</span><a name="line.11"></a>
<span class="sourceLineNo">012</span>import org.slf4j.Logger;<a name="line.12"></a>
<span class="sourceLineNo">013</span>import org.slf4j.LoggerFactory;<a name="line.13"></a>
<span class="sourceLineNo">014</span><a name="line.14"></a>
<span class="sourceLineNo">015</span><a name="line.15"></a>
<span class="sourceLineNo">016</span>/**<a name="line.16"></a>
<span class="sourceLineNo">017</span> * This class is used as a global (system) lock preventing other processes from<a name="line.17"></a>
<span class="sourceLineNo">018</span> * using the same camera while it's open. Whenever webcam is open there is a<a name="line.18"></a>
<span class="sourceLineNo">019</span> * thread running in background which updates the lock once per 2 seconds. Lock<a name="line.19"></a>
<span class="sourceLineNo">020</span> * is being released whenever webcam is either closed or completely disposed.<a name="line.20"></a>
<span class="sourceLineNo">021</span> * Lock will remain for at least 2 seconds in case when JVM has not been<a name="line.21"></a>
<span class="sourceLineNo">022</span> * gracefully terminated (due to SIGSEGV, SIGTERM, etc).<a name="line.22"></a>
<span class="sourceLineNo">023</span> * <a name="line.23"></a>
<span class="sourceLineNo">024</span> * @author Bartosz Firyn (sarxos)<a name="line.24"></a>
<span class="sourceLineNo">025</span> */<a name="line.25"></a>
<span class="sourceLineNo">026</span>public class WebcamLock {<a name="line.26"></a>
<span class="sourceLineNo">027</span><a name="line.27"></a>
<span class="sourceLineNo">028</span>        /**<a name="line.28"></a>
<span class="sourceLineNo">029</span>         * Logger.<a name="line.29"></a>
<span class="sourceLineNo">030</span>         */<a name="line.30"></a>
<span class="sourceLineNo">031</span>        private static final Logger LOG = LoggerFactory.getLogger(WebcamLock.class);<a name="line.31"></a>
<span class="sourceLineNo">032</span><a name="line.32"></a>
<span class="sourceLineNo">033</span>        /**<a name="line.33"></a>
<span class="sourceLineNo">034</span>         * Update interval (ms).<a name="line.34"></a>
<span class="sourceLineNo">035</span>         */<a name="line.35"></a>
<span class="sourceLineNo">036</span>        public static final long INTERVAL = 2000;<a name="line.36"></a>
<span class="sourceLineNo">037</span><a name="line.37"></a>
<span class="sourceLineNo">038</span>        /**<a name="line.38"></a>
<span class="sourceLineNo">039</span>         * Used to update lock state.<a name="line.39"></a>
<span class="sourceLineNo">040</span>         * <a name="line.40"></a>
<span class="sourceLineNo">041</span>         * @author sarxos<a name="line.41"></a>
<span class="sourceLineNo">042</span>         */<a name="line.42"></a>
<span class="sourceLineNo">043</span>        private class LockUpdater extends Thread {<a name="line.43"></a>
<span class="sourceLineNo">044</span><a name="line.44"></a>
<span class="sourceLineNo">045</span>                public LockUpdater() {<a name="line.45"></a>
<span class="sourceLineNo">046</span>                        super();<a name="line.46"></a>
<span class="sourceLineNo">047</span>                        setName(String.format("webcam-lock-[%s]", webcam.getName()));<a name="line.47"></a>
<span class="sourceLineNo">048</span>                        setDaemon(true);<a name="line.48"></a>
<span class="sourceLineNo">049</span>                        setUncaughtExceptionHandler(WebcamExceptionHandler.getInstance());<a name="line.49"></a>
<span class="sourceLineNo">050</span>                }<a name="line.50"></a>
<span class="sourceLineNo">051</span><a name="line.51"></a>
<span class="sourceLineNo">052</span>                @Override<a name="line.52"></a>
<span class="sourceLineNo">053</span>                public void run() {<a name="line.53"></a>
<span class="sourceLineNo">054</span>                        do {<a name="line.54"></a>
<span class="sourceLineNo">055</span>                                if (disabled.get()) {<a name="line.55"></a>
<span class="sourceLineNo">056</span>                                        return;<a name="line.56"></a>
<span class="sourceLineNo">057</span>                                }<a name="line.57"></a>
<span class="sourceLineNo">058</span>                                update();<a name="line.58"></a>
<span class="sourceLineNo">059</span>                                try {<a name="line.59"></a>
<span class="sourceLineNo">060</span>                                        Thread.sleep(INTERVAL);<a name="line.60"></a>
<span class="sourceLineNo">061</span>                                } catch (InterruptedException e) {<a name="line.61"></a>
<span class="sourceLineNo">062</span>                                        LOG.debug("Lock updater has been interrupted");<a name="line.62"></a>
<span class="sourceLineNo">063</span>                                        return;<a name="line.63"></a>
<span class="sourceLineNo">064</span>                                }<a name="line.64"></a>
<span class="sourceLineNo">065</span>                        } while (locked.get());<a name="line.65"></a>
<span class="sourceLineNo">066</span>                }<a name="line.66"></a>
<span class="sourceLineNo">067</span><a name="line.67"></a>
<span class="sourceLineNo">068</span>        }<a name="line.68"></a>
<span class="sourceLineNo">069</span><a name="line.69"></a>
<span class="sourceLineNo">070</span>        /**<a name="line.70"></a>
<span class="sourceLineNo">071</span>         * And the Webcam we will be locking.<a name="line.71"></a>
<span class="sourceLineNo">072</span>         */<a name="line.72"></a>
<span class="sourceLineNo">073</span>        private final Webcam webcam;<a name="line.73"></a>
<span class="sourceLineNo">074</span><a name="line.74"></a>
<span class="sourceLineNo">075</span>        /**<a name="line.75"></a>
<span class="sourceLineNo">076</span>         * Updater thread. It will update the lock value in fixed interval.<a name="line.76"></a>
<span class="sourceLineNo">077</span>         */<a name="line.77"></a>
<span class="sourceLineNo">078</span>        private Thread updater = null;<a name="line.78"></a>
<span class="sourceLineNo">079</span><a name="line.79"></a>
<span class="sourceLineNo">080</span>        /**<a name="line.80"></a>
<span class="sourceLineNo">081</span>         * Is webcam locked (local, not cross-VM variable).<a name="line.81"></a>
<span class="sourceLineNo">082</span>         */<a name="line.82"></a>
<span class="sourceLineNo">083</span>        private AtomicBoolean locked = new AtomicBoolean(false);<a name="line.83"></a>
<span class="sourceLineNo">084</span><a name="line.84"></a>
<span class="sourceLineNo">085</span>        /**<a name="line.85"></a>
<span class="sourceLineNo">086</span>         * Is lock completely disabled.<a name="line.86"></a>
<span class="sourceLineNo">087</span>         */<a name="line.87"></a>
<span class="sourceLineNo">088</span>        private AtomicBoolean disabled = new AtomicBoolean(false);<a name="line.88"></a>
<span class="sourceLineNo">089</span><a name="line.89"></a>
<span class="sourceLineNo">090</span>        /**<a name="line.90"></a>
<span class="sourceLineNo">091</span>         * Lock file.<a name="line.91"></a>
<span class="sourceLineNo">092</span>         */<a name="line.92"></a>
<span class="sourceLineNo">093</span>        private File lock = null;<a name="line.93"></a>
<span class="sourceLineNo">094</span><a name="line.94"></a>
<span class="sourceLineNo">095</span>        /**<a name="line.95"></a>
<span class="sourceLineNo">096</span>         * Creates global webcam lock.<a name="line.96"></a>
<span class="sourceLineNo">097</span>         * <a name="line.97"></a>
<span class="sourceLineNo">098</span>         * @param webcam the webcam instance to be locked<a name="line.98"></a>
<span class="sourceLineNo">099</span>         */<a name="line.99"></a>
<span class="sourceLineNo">100</span>        protected WebcamLock(Webcam webcam) {<a name="line.100"></a>
<span class="sourceLineNo">101</span>                super();<a name="line.101"></a>
<span class="sourceLineNo">102</span>                this.webcam = webcam;<a name="line.102"></a>
<span class="sourceLineNo">103</span>                this.lock = new File(System.getProperty("java.io.tmpdir"), getLockName());<a name="line.103"></a>
<span class="sourceLineNo">104</span>                this.lock.deleteOnExit();<a name="line.104"></a>
<span class="sourceLineNo">105</span>        }<a name="line.105"></a>
<span class="sourceLineNo">106</span><a name="line.106"></a>
<span class="sourceLineNo">107</span>        private String getLockName() {<a name="line.107"></a>
<span class="sourceLineNo">108</span>                return String.format(".webcam-lock-%d", Math.abs(webcam.getName().hashCode()));<a name="line.108"></a>
<span class="sourceLineNo">109</span>        }<a name="line.109"></a>
<span class="sourceLineNo">110</span><a name="line.110"></a>
<span class="sourceLineNo">111</span>        private void write(long value) {<a name="line.111"></a>
<span class="sourceLineNo">112</span><a name="line.112"></a>
<span class="sourceLineNo">113</span>                if (disabled.get()) {<a name="line.113"></a>
<span class="sourceLineNo">114</span>                        return;<a name="line.114"></a>
<span class="sourceLineNo">115</span>                }<a name="line.115"></a>
<span class="sourceLineNo">116</span><a name="line.116"></a>
<span class="sourceLineNo">117</span>                String name = getLockName();<a name="line.117"></a>
<span class="sourceLineNo">118</span><a name="line.118"></a>
<span class="sourceLineNo">119</span>                File tmp = null;<a name="line.119"></a>
<span class="sourceLineNo">120</span>                DataOutputStream dos = null;<a name="line.120"></a>
<span class="sourceLineNo">121</span><a name="line.121"></a>
<span class="sourceLineNo">122</span>                try {<a name="line.122"></a>
<span class="sourceLineNo">123</span><a name="line.123"></a>
<span class="sourceLineNo">124</span>                        tmp = File.createTempFile(String.format("%s-tmp", name), "");<a name="line.124"></a>
<span class="sourceLineNo">125</span>                        tmp.deleteOnExit();<a name="line.125"></a>
<span class="sourceLineNo">126</span><a name="line.126"></a>
<span class="sourceLineNo">127</span>                        dos = new DataOutputStream(new FileOutputStream(tmp));<a name="line.127"></a>
<span class="sourceLineNo">128</span>                        dos.writeLong(value);<a name="line.128"></a>
<span class="sourceLineNo">129</span>                        dos.flush();<a name="line.129"></a>
<span class="sourceLineNo">130</span><a name="line.130"></a>
<span class="sourceLineNo">131</span>                } catch (IOException e) {<a name="line.131"></a>
<span class="sourceLineNo">132</span>                        throw new RuntimeException(e);<a name="line.132"></a>
<span class="sourceLineNo">133</span>                } finally {<a name="line.133"></a>
<span class="sourceLineNo">134</span>                        if (dos != null) {<a name="line.134"></a>
<span class="sourceLineNo">135</span>                                try {<a name="line.135"></a>
<span class="sourceLineNo">136</span>                                        dos.close();<a name="line.136"></a>
<span class="sourceLineNo">137</span>                                } catch (IOException e) {<a name="line.137"></a>
<span class="sourceLineNo">138</span>                                        throw new RuntimeException(e);<a name="line.138"></a>
<span class="sourceLineNo">139</span>                                }<a name="line.139"></a>
<span class="sourceLineNo">140</span>                        }<a name="line.140"></a>
<span class="sourceLineNo">141</span>                }<a name="line.141"></a>
<span class="sourceLineNo">142</span><a name="line.142"></a>
<span class="sourceLineNo">143</span>                if (!locked.get()) {<a name="line.143"></a>
<span class="sourceLineNo">144</span>                        return;<a name="line.144"></a>
<span class="sourceLineNo">145</span>                }<a name="line.145"></a>
<span class="sourceLineNo">146</span><a name="line.146"></a>
<span class="sourceLineNo">147</span>                if (tmp.renameTo(lock)) {<a name="line.147"></a>
<span class="sourceLineNo">148</span><a name="line.148"></a>
<span class="sourceLineNo">149</span>                        // atomic rename operation can fail (mostly on Windows), so we<a name="line.149"></a>
<span class="sourceLineNo">150</span>                        // simply jump out the method if it succeed, or try to rewrite<a name="line.150"></a>
<span class="sourceLineNo">151</span>                        // content using streams if it fail<a name="line.151"></a>
<span class="sourceLineNo">152</span><a name="line.152"></a>
<span class="sourceLineNo">153</span>                        return;<a name="line.153"></a>
<span class="sourceLineNo">154</span>                } else {<a name="line.154"></a>
<span class="sourceLineNo">155</span><a name="line.155"></a>
<span class="sourceLineNo">156</span>                        // create lock file if not exist<a name="line.156"></a>
<span class="sourceLineNo">157</span><a name="line.157"></a>
<span class="sourceLineNo">158</span>                        if (!lock.exists()) {<a name="line.158"></a>
<span class="sourceLineNo">159</span>                                try {<a name="line.159"></a>
<span class="sourceLineNo">160</span>                                        if (lock.createNewFile()) {<a name="line.160"></a>
<span class="sourceLineNo">161</span>                                                LOG.info("Lock file {} for {} has been created", lock, webcam);<a name="line.161"></a>
<span class="sourceLineNo">162</span>                                        } else {<a name="line.162"></a>
<span class="sourceLineNo">163</span>                                                throw new RuntimeException("Not able to create file " + lock);<a name="line.163"></a>
<span class="sourceLineNo">164</span>                                        }<a name="line.164"></a>
<span class="sourceLineNo">165</span>                                } catch (IOException e) {<a name="line.165"></a>
<span class="sourceLineNo">166</span>                                        throw new RuntimeException(e);<a name="line.166"></a>
<span class="sourceLineNo">167</span>                                }<a name="line.167"></a>
<span class="sourceLineNo">168</span>                        }<a name="line.168"></a>
<span class="sourceLineNo">169</span><a name="line.169"></a>
<span class="sourceLineNo">170</span>                        FileOutputStream fos = null;<a name="line.170"></a>
<span class="sourceLineNo">171</span>                        FileInputStream fis = null;<a name="line.171"></a>
<span class="sourceLineNo">172</span><a name="line.172"></a>
<span class="sourceLineNo">173</span>                        int k = 0;<a name="line.173"></a>
<span class="sourceLineNo">174</span>                        int n = -1;<a name="line.174"></a>
<span class="sourceLineNo">175</span>                        byte[] buffer = new byte[8];<a name="line.175"></a>
<span class="sourceLineNo">176</span>                        boolean rewritten = false;<a name="line.176"></a>
<span class="sourceLineNo">177</span><a name="line.177"></a>
<span class="sourceLineNo">178</span>                        // rewrite temporary file content to lock, try max 5 times<a name="line.178"></a>
<span class="sourceLineNo">179</span><a name="line.179"></a>
<span class="sourceLineNo">180</span>                        synchronized (webcam) {<a name="line.180"></a>
<span class="sourceLineNo">181</span>                                do {<a name="line.181"></a>
<span class="sourceLineNo">182</span>                                        try {<a name="line.182"></a>
<span class="sourceLineNo">183</span><a name="line.183"></a>
<span class="sourceLineNo">184</span>                                                fos = new FileOutputStream(lock);<a name="line.184"></a>
<span class="sourceLineNo">185</span>                                                fis = new FileInputStream(tmp);<a name="line.185"></a>
<span class="sourceLineNo">186</span>                                                while ((n = fis.read(buffer)) != -1) {<a name="line.186"></a>
<span class="sourceLineNo">187</span>                                                        fos.write(buffer, 0, n);<a name="line.187"></a>
<span class="sourceLineNo">188</span>                                                }<a name="line.188"></a>
<span class="sourceLineNo">189</span>                                                rewritten = true;<a name="line.189"></a>
<span class="sourceLineNo">190</span><a name="line.190"></a>
<span class="sourceLineNo">191</span>                                        } catch (IOException e) {<a name="line.191"></a>
<span class="sourceLineNo">192</span>                                                LOG.debug("Not able to rewrite lock file", e);<a name="line.192"></a>
<span class="sourceLineNo">193</span>                                        } finally {<a name="line.193"></a>
<span class="sourceLineNo">194</span>                                                if (fos != null) {<a name="line.194"></a>
<span class="sourceLineNo">195</span>                                                        try {<a name="line.195"></a>
<span class="sourceLineNo">196</span>                                                                fos.close();<a name="line.196"></a>
<span class="sourceLineNo">197</span>                                                        } catch (IOException e) {<a name="line.197"></a>
<span class="sourceLineNo">198</span>                                                                throw new RuntimeException(e);<a name="line.198"></a>
<span class="sourceLineNo">199</span>                                                        }<a name="line.199"></a>
<span class="sourceLineNo">200</span>                                                }<a name="line.200"></a>
<span class="sourceLineNo">201</span>                                                if (fis != null) {<a name="line.201"></a>
<span class="sourceLineNo">202</span>                                                        try {<a name="line.202"></a>
<span class="sourceLineNo">203</span>                                                                fis.close();<a name="line.203"></a>
<span class="sourceLineNo">204</span>                                                        } catch (IOException e) {<a name="line.204"></a>
<span class="sourceLineNo">205</span>                                                                throw new RuntimeException(e);<a name="line.205"></a>
<span class="sourceLineNo">206</span>                                                        }<a name="line.206"></a>
<span class="sourceLineNo">207</span>                                                }<a name="line.207"></a>
<span class="sourceLineNo">208</span>                                        }<a name="line.208"></a>
<span class="sourceLineNo">209</span>                                        if (rewritten) {<a name="line.209"></a>
<span class="sourceLineNo">210</span>                                                break;<a name="line.210"></a>
<span class="sourceLineNo">211</span>                                        }<a name="line.211"></a>
<span class="sourceLineNo">212</span>                                } while (k++ &lt; 5);<a name="line.212"></a>
<span class="sourceLineNo">213</span>                        }<a name="line.213"></a>
<span class="sourceLineNo">214</span><a name="line.214"></a>
<span class="sourceLineNo">215</span>                        if (!rewritten) {<a name="line.215"></a>
<span class="sourceLineNo">216</span>                                throw new WebcamException("Not able to write lock file");<a name="line.216"></a>
<span class="sourceLineNo">217</span>                        }<a name="line.217"></a>
<span class="sourceLineNo">218</span><a name="line.218"></a>
<span class="sourceLineNo">219</span>                        // remove temporary file<a name="line.219"></a>
<span class="sourceLineNo">220</span><a name="line.220"></a>
<span class="sourceLineNo">221</span>                        if (!tmp.delete()) {<a name="line.221"></a>
<span class="sourceLineNo">222</span>                                tmp.deleteOnExit();<a name="line.222"></a>
<span class="sourceLineNo">223</span>                        }<a name="line.223"></a>
<span class="sourceLineNo">224</span>                }<a name="line.224"></a>
<span class="sourceLineNo">225</span><a name="line.225"></a>
<span class="sourceLineNo">226</span>        }<a name="line.226"></a>
<span class="sourceLineNo">227</span><a name="line.227"></a>
<span class="sourceLineNo">228</span>        private long read() {<a name="line.228"></a>
<span class="sourceLineNo">229</span><a name="line.229"></a>
<span class="sourceLineNo">230</span>                if (disabled.get()) {<a name="line.230"></a>
<span class="sourceLineNo">231</span>                        return -1;<a name="line.231"></a>
<span class="sourceLineNo">232</span>                }<a name="line.232"></a>
<span class="sourceLineNo">233</span><a name="line.233"></a>
<span class="sourceLineNo">234</span>                DataInputStream dis = null;<a name="line.234"></a>
<span class="sourceLineNo">235</span><a name="line.235"></a>
<span class="sourceLineNo">236</span>                long value = -1;<a name="line.236"></a>
<span class="sourceLineNo">237</span>                boolean broken = false;<a name="line.237"></a>
<span class="sourceLineNo">238</span><a name="line.238"></a>
<span class="sourceLineNo">239</span>                synchronized (webcam) {<a name="line.239"></a>
<span class="sourceLineNo">240</span><a name="line.240"></a>
<span class="sourceLineNo">241</span>                        try {<a name="line.241"></a>
<span class="sourceLineNo">242</span>                                value = (dis = new DataInputStream(new FileInputStream(lock))).readLong();<a name="line.242"></a>
<span class="sourceLineNo">243</span>                        } catch (EOFException e) {<a name="line.243"></a>
<span class="sourceLineNo">244</span>                                LOG.debug("Webcam lock is broken - EOF when reading long variable from stream", e);<a name="line.244"></a>
<span class="sourceLineNo">245</span>                                broken = true;<a name="line.245"></a>
<span class="sourceLineNo">246</span>                        } catch (IOException e) {<a name="line.246"></a>
<span class="sourceLineNo">247</span>                                throw new RuntimeException(e);<a name="line.247"></a>
<span class="sourceLineNo">248</span>                        } finally {<a name="line.248"></a>
<span class="sourceLineNo">249</span>                                if (dis != null) {<a name="line.249"></a>
<span class="sourceLineNo">250</span>                                        try {<a name="line.250"></a>
<span class="sourceLineNo">251</span>                                                dis.close();<a name="line.251"></a>
<span class="sourceLineNo">252</span>                                        } catch (IOException e) {<a name="line.252"></a>
<span class="sourceLineNo">253</span>                                                throw new RuntimeException(e);<a name="line.253"></a>
<span class="sourceLineNo">254</span>                                        }<a name="line.254"></a>
<span class="sourceLineNo">255</span>                                }<a name="line.255"></a>
<span class="sourceLineNo">256</span>                        }<a name="line.256"></a>
<span class="sourceLineNo">257</span><a name="line.257"></a>
<span class="sourceLineNo">258</span>                        if (broken) {<a name="line.258"></a>
<span class="sourceLineNo">259</span>                                LOG.warn("Lock file {} for {} is broken - recreating it", lock, webcam);<a name="line.259"></a>
<span class="sourceLineNo">260</span>                                write(-1);<a name="line.260"></a>
<span class="sourceLineNo">261</span>                        }<a name="line.261"></a>
<span class="sourceLineNo">262</span>                }<a name="line.262"></a>
<span class="sourceLineNo">263</span><a name="line.263"></a>
<span class="sourceLineNo">264</span>                return value;<a name="line.264"></a>
<span class="sourceLineNo">265</span>        }<a name="line.265"></a>
<span class="sourceLineNo">266</span><a name="line.266"></a>
<span class="sourceLineNo">267</span>        private void update() {<a name="line.267"></a>
<span class="sourceLineNo">268</span><a name="line.268"></a>
<span class="sourceLineNo">269</span>                if (disabled.get()) {<a name="line.269"></a>
<span class="sourceLineNo">270</span>                        return;<a name="line.270"></a>
<span class="sourceLineNo">271</span>                }<a name="line.271"></a>
<span class="sourceLineNo">272</span><a name="line.272"></a>
<span class="sourceLineNo">273</span>                write(System.currentTimeMillis());<a name="line.273"></a>
<span class="sourceLineNo">274</span>        }<a name="line.274"></a>
<span class="sourceLineNo">275</span><a name="line.275"></a>
<span class="sourceLineNo">276</span>        /**<a name="line.276"></a>
<span class="sourceLineNo">277</span>         * Lock webcam.<a name="line.277"></a>
<span class="sourceLineNo">278</span>         */<a name="line.278"></a>
<span class="sourceLineNo">279</span>        public void lock() {<a name="line.279"></a>
<span class="sourceLineNo">280</span><a name="line.280"></a>
<span class="sourceLineNo">281</span>                if (disabled.get()) {<a name="line.281"></a>
<span class="sourceLineNo">282</span>                        return;<a name="line.282"></a>
<span class="sourceLineNo">283</span>                }<a name="line.283"></a>
<span class="sourceLineNo">284</span><a name="line.284"></a>
<span class="sourceLineNo">285</span>                if (isLocked()) {<a name="line.285"></a>
<span class="sourceLineNo">286</span>                        throw new WebcamLockException(String.format("Webcam %s has already been locked", webcam.getName()));<a name="line.286"></a>
<span class="sourceLineNo">287</span>                }<a name="line.287"></a>
<span class="sourceLineNo">288</span><a name="line.288"></a>
<span class="sourceLineNo">289</span>                if (!locked.compareAndSet(false, true)) {<a name="line.289"></a>
<span class="sourceLineNo">290</span>                        return;<a name="line.290"></a>
<span class="sourceLineNo">291</span>                }<a name="line.291"></a>
<span class="sourceLineNo">292</span><a name="line.292"></a>
<span class="sourceLineNo">293</span>                LOG.debug("Lock {}", webcam);<a name="line.293"></a>
<span class="sourceLineNo">294</span><a name="line.294"></a>
<span class="sourceLineNo">295</span>                update();<a name="line.295"></a>
<span class="sourceLineNo">296</span><a name="line.296"></a>
<span class="sourceLineNo">297</span>                updater = new LockUpdater();<a name="line.297"></a>
<span class="sourceLineNo">298</span>                updater.start();<a name="line.298"></a>
<span class="sourceLineNo">299</span>        }<a name="line.299"></a>
<span class="sourceLineNo">300</span><a name="line.300"></a>
<span class="sourceLineNo">301</span>        /**<a name="line.301"></a>
<span class="sourceLineNo">302</span>         * Completely disable locking mechanism. After this method is invoked, the<a name="line.302"></a>
<span class="sourceLineNo">303</span>         * lock will not have any effect on the webcam runtime.<a name="line.303"></a>
<span class="sourceLineNo">304</span>         */<a name="line.304"></a>
<span class="sourceLineNo">305</span>        public void disable() {<a name="line.305"></a>
<span class="sourceLineNo">306</span>                if (disabled.compareAndSet(false, true)) {<a name="line.306"></a>
<span class="sourceLineNo">307</span>                        LOG.info("Locking mechanism has been disabled in {}", webcam);<a name="line.307"></a>
<span class="sourceLineNo">308</span>                        if (updater != null) {<a name="line.308"></a>
<span class="sourceLineNo">309</span>                                updater.interrupt();<a name="line.309"></a>
<span class="sourceLineNo">310</span>                        }<a name="line.310"></a>
<span class="sourceLineNo">311</span>                }<a name="line.311"></a>
<span class="sourceLineNo">312</span>        }<a name="line.312"></a>
<span class="sourceLineNo">313</span><a name="line.313"></a>
<span class="sourceLineNo">314</span>        /**<a name="line.314"></a>
<span class="sourceLineNo">315</span>         * Unlock webcam.<a name="line.315"></a>
<span class="sourceLineNo">316</span>         */<a name="line.316"></a>
<span class="sourceLineNo">317</span>        public void unlock() {<a name="line.317"></a>
<span class="sourceLineNo">318</span><a name="line.318"></a>
<span class="sourceLineNo">319</span>                // do nothing when lock disabled<a name="line.319"></a>
<span class="sourceLineNo">320</span><a name="line.320"></a>
<span class="sourceLineNo">321</span>                if (disabled.get()) {<a name="line.321"></a>
<span class="sourceLineNo">322</span>                        return;<a name="line.322"></a>
<span class="sourceLineNo">323</span>                }<a name="line.323"></a>
<span class="sourceLineNo">324</span><a name="line.324"></a>
<span class="sourceLineNo">325</span>                if (!locked.compareAndSet(true, false)) {<a name="line.325"></a>
<span class="sourceLineNo">326</span>                        return;<a name="line.326"></a>
<span class="sourceLineNo">327</span>                }<a name="line.327"></a>
<span class="sourceLineNo">328</span><a name="line.328"></a>
<span class="sourceLineNo">329</span>                LOG.debug("Unlock {}", webcam);<a name="line.329"></a>
<span class="sourceLineNo">330</span><a name="line.330"></a>
<span class="sourceLineNo">331</span>                updater.interrupt();<a name="line.331"></a>
<span class="sourceLineNo">332</span><a name="line.332"></a>
<span class="sourceLineNo">333</span>                write(-1);<a name="line.333"></a>
<span class="sourceLineNo">334</span><a name="line.334"></a>
<span class="sourceLineNo">335</span>                if (!lock.delete()) {<a name="line.335"></a>
<span class="sourceLineNo">336</span>                        lock.deleteOnExit();<a name="line.336"></a>
<span class="sourceLineNo">337</span>                }<a name="line.337"></a>
<span class="sourceLineNo">338</span>        }<a name="line.338"></a>
<span class="sourceLineNo">339</span><a name="line.339"></a>
<span class="sourceLineNo">340</span>        /**<a name="line.340"></a>
<span class="sourceLineNo">341</span>         * Check if webcam is locked.<a name="line.341"></a>
<span class="sourceLineNo">342</span>         * <a name="line.342"></a>
<span class="sourceLineNo">343</span>         * @return True if webcam is locked, false otherwise<a name="line.343"></a>
<span class="sourceLineNo">344</span>         */<a name="line.344"></a>
<span class="sourceLineNo">345</span>        public boolean isLocked() {<a name="line.345"></a>
<span class="sourceLineNo">346</span><a name="line.346"></a>
<span class="sourceLineNo">347</span>                // always return false when lock is disabled<a name="line.347"></a>
<span class="sourceLineNo">348</span><a name="line.348"></a>
<span class="sourceLineNo">349</span>                if (disabled.get()) {<a name="line.349"></a>
<span class="sourceLineNo">350</span>                        return false;<a name="line.350"></a>
<span class="sourceLineNo">351</span>                }<a name="line.351"></a>
<span class="sourceLineNo">352</span><a name="line.352"></a>
<span class="sourceLineNo">353</span>                // check if locked by current process<a name="line.353"></a>
<span class="sourceLineNo">354</span><a name="line.354"></a>
<span class="sourceLineNo">355</span>                if (locked.get()) {<a name="line.355"></a>
<span class="sourceLineNo">356</span>                        return true;<a name="line.356"></a>
<span class="sourceLineNo">357</span>                }<a name="line.357"></a>
<span class="sourceLineNo">358</span><a name="line.358"></a>
<span class="sourceLineNo">359</span>                // check if locked by other process<a name="line.359"></a>
<span class="sourceLineNo">360</span><a name="line.360"></a>
<span class="sourceLineNo">361</span>                if (!lock.exists()) {<a name="line.361"></a>
<span class="sourceLineNo">362</span>                        return false;<a name="line.362"></a>
<span class="sourceLineNo">363</span>                }<a name="line.363"></a>
<span class="sourceLineNo">364</span><a name="line.364"></a>
<span class="sourceLineNo">365</span>                long now = System.currentTimeMillis();<a name="line.365"></a>
<span class="sourceLineNo">366</span>                long tsp = read();<a name="line.366"></a>
<span class="sourceLineNo">367</span><a name="line.367"></a>
<span class="sourceLineNo">368</span>                LOG.trace("Lock timestamp {} now {} for {}", tsp, now, webcam);<a name="line.368"></a>
<span class="sourceLineNo">369</span><a name="line.369"></a>
<span class="sourceLineNo">370</span>                if (tsp &gt; now - INTERVAL * 2) {<a name="line.370"></a>
<span class="sourceLineNo">371</span>                        return true;<a name="line.371"></a>
<span class="sourceLineNo">372</span>                }<a name="line.372"></a>
<span class="sourceLineNo">373</span><a name="line.373"></a>
<span class="sourceLineNo">374</span>                return false;<a name="line.374"></a>
<span class="sourceLineNo">375</span>        }<a name="line.375"></a>
<span class="sourceLineNo">376</span>}<a name="line.376"></a>




























































</pre>
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